Speed change gear system

ABSTRACT

A speed change gear system for providing at least four forward drive speed ranges and one reverse drive speed range includes three planetary gear sets of the single-pinion type, three clutches, and two brakes. As a result of the coupling and uncoupling of the clutches and brakes, the movable elements of each of the planetary gear sets are suitably coupled so as to attain the various speed ranges.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to speed change gear systems andmore particularly to a speed change gear system which is adapted forapplication with fluid couplings utilized within motor vehicles,especially automobiles.

2. Description of the Prior Art

It is preferable to utilize at least four gear sets within the speedchange gear systems of large automotive vehicles, such as for example,trucks and buses, and in order to attain a speed change mechanism havingmore than four speed shifts, three, four or even more sets of simple,single-pinion or double-pinion type planetary gear sets have heretoforebeen combined. While the combination of these gears may be widelyvaried, it is preferable however that the following conditions beattained:

(1) The output shaft should be coupled to the same elements within eachspeed range.

(2) In order to reduce the circumferential speed of the bearings of eachelement of the planetary gear set, the number of its revolutions shouldbe small.

(3) The tooth load, that is, the tangential force of each element,should be small so as to maintain the strength of the gear teeth.

(4) The gear set should always attain meshing conditions for the numberof teeth required. For example, the sun gear, whose diameter is to beminimized, as well as each planetary pinion gear, should have thenecessary number of teeth.

(5) Within each planetary gear set, the coupling relationship among theelements should be simple and the distance from each other should besmall.

(6) During speed shifts, wherein frictional coupling means are utilizedduring forward drive, such speed shifts should be available through onecoupling means alone.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a speedchange gear system which provides at least four speed ranges for forwarddrive and one speed range for reverse drive by the use of threeplanetary gear sets of the single-pinion type, three clutches, and twobrakes, whereby the movable members of each of the planetary gear setsare suitably coupled as a result of the coupling or uncoupling of theclutches and brakes so as to attain the various speed ranges.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and attendant advantages of the presentinvention will be more fully appreciated as the same becomes betterunderstood from the following detailed description when considered inconjunction with the accompanying drawings, in which like referencecharacters designate like or corresponding parts throughout the severalviews, and wherein:

FIG. 1 is a schematic view of one embodiment of a speed change gearsystem constructed in accordance with the present invention anddisclosing its cooperative parts;

FIG. 2 is a schematic view similar to that of FIG. 1 showing howeveranother embodiment of the present invention;

FIG. 3 is a schematic view similar to that of FIG. 1 showing however yetanother embodiment of the present invention;

FIG. 4 is a schematic view similar to that of FIG. 1 showing howeverstill another embodiment of the present invention;

FIG. 5 is a schematic view similar to that of FIG. 1 showing yet stillanother embodiment of the present invention;

FIG. 6 is a schematic view similar to that of FIG. 1 showing however afurther embodiment of the present invention;

FIG. 7 is a schematic view similar to that of FIG. 1 showing however ayet further embodiment of the present invention;

FIG. 8 is a schematic view similar to that of FIG. 1 showing however astill further embodiment of the present invention; and

FIG. 9 is a schematic view similar to that of FIG. 1 showing however ayet still further embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring now to the drawings and more particularly to FIG. 1 thereof,the disclosed speed change gear system includes a first planetary gearset, generally indicated by the reference character X₁, of thesingle-pinion type, a second planetary gear set, generally indicated bythe reference character X₂, of the single-pinion type, and a thirdplanetary gear set, generally indicated by the reference character X₃,also of the single-pinion type, all of which are interposed between aninput shaft and an output shaft.

The first planetary gear set X₁ is seen to comprise a first sun gear S₁,a first planetary gear P₁ engaged with the first sun gear S₁, a firstring gear RG₁ enmeshed with the first planetary gear P₁, and a firstcarrier C₁ rotatably supporting the first planetary gear P₁, while thesecond planetary gear set X₂ similarly includes a second sun gear S₂, asecond planetary gear P₂ engaged with the second sun gear S₂, a secondring gear RG₂ enmeshed with the second planetary gear P₂, and a secondcarrier C₂ rotatably supporting the second planetary gear P₂.

The third planetary gear set X₃ includes a third sun gear S₃, a thirdplanetary gear P₃ engaged with the third sun gear S₃, a third ring gearRG₃ enmeshed with the third planetary gear P₃, and a third carrier C₃rotatably supporting the third planetary gear P₃. It will be furtherseen that the first sun gear S₁ is drivingly connected with the thirdsun gear S₃, as is the first ring gear RG₁ with the second ring gearRG₂, the second sun gear S₂ with the third ring gear RG₃, and the secondcarrier C₂ with the third carrier C₃ as well as with the output shaft. Afirst clutch CL₁ serves to couple or uncouple the first sun gear S₁ andthe third sun gear S₃ with the input shaft, while a second clutch CL₂serves to couple or uncouple the first carrier C₁ with the input shaft,and a third clutch CL.sub. 3 serves to couple or uncouple the first ringgear RG₁ and the second ring gear RG₂ with the input shaft.

A first brake B₁ is provided so as to be capable of locking the firstring gear RG₁ and the second ring gear RG₂ to the gear casing when thefirst brake is actuated, and similarly, a second brake B₂ is provided soas to be capable of locking the second sun gear S₂ and the third ringgear RG₃ to the casing when the same is actuated.

The following equations are given as characteristic of the planetarygear sets X₁, X₂ and X₃ :

    n.sub.rg.sbsb.1 -(1 + i.sub.1)n.sub.c.sbsb.1 + i.sub.1 n.sub.s.sbsb.1 = 0

    n.sub.rg.sbsb.2 -(1 + i.sub.2)n.sub.c.sbsb.2 + i.sub.2 n.sub.s.sbsb.2 = 0

    n.sub.rg.sbsb.3 -(1 + i.sub.3) n.sub.c.sbsb.3 = i.sub.3 n.sub.s.sbsb.3 =0

wherein:

N_(RG).sbsb.1,N_(RG).sbsb.2, N_(RG).sbsb.3 =the number of revolutions ofthe first, second and third ring gears;

N_(C).sbsb.1, N_(C).sbsb.2 , N_(C).sbsb.3 =the number of revolutions ofthe first, second

and third carriers;

N_(S).sbsb.1, N_(S).sbsb.2, N_(S).sbsb.3 =the number of revolutions ofthe first, second and third sun gears; and

I₁, I₂, I₃ =the radial ratios of each ring gear with respect to each sungear.

                  TABLE 1A                                                        ______________________________________                                        CL1     CL2    CL3    B1   B2   Reduction Gear Ratio                          ______________________________________                                        F1   ·              ·                                                                         3.82                                        F2          ·       ·                                                                         2.21                                        F3                 ·                                                                              ·                                                                         1.48                                        F4   ·    ·     1.00                                        R1   ·         ·                                                                              -4.82                                       R2          ·  ·                                                                              -1.50                                       ______________________________________                                    

Within this embodiment, the radial ratios within each speed range are I₁= 0.452, I₂ = 0.484, I₃ = 0.355, and Table 1A shows the relationshipbetween the operation of clutches CL₁, CL₂ and CL₃ and brakes B₁, and B₂relative to the gear ratio within each speed range, wherein F_(n) (n =1, 2, 3, . . .) designates a forward speed range, such as, for example,F₁ designates the first forward speed range, F₂ designates the secondforward speed range, and the like, and R_(n) (n = 1, 2, . . .)designates a reverse speed range, such as, for example, R₁ designatesthe first reverse speed range, and it may be seen that a reduction gearratio of 1 : 1.00 can be obtained by desirably and selectively employingtwo of the clutches CL₁, CL₂ and CL₃. Table 1B shows the relationshipregarding the number or revolutions and the tangential forces of each ofthe elements of the planetary gear sets within each speed range, theratio of the number of revolutions being based upon the assumption thatthe number of revolutions of the input shaft is 1, while the designatedtangential forces are based upon the assumption that the input shafttorque exerted upon the ring gear is 1, the tangential forces of theplanetary gears being equal to those of the sun gears and the ringgears.

                                      TABLE 1B                                    __________________________________________________________________________    B   X1           X2            X3                                             A   S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3                                  __________________________________________________________________________      N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                               F1                                                                              W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                  N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                               F2                                                                              W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                  N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                               F3                                                                              W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                               R1                                                                              W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                  N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                               R2                                                                              W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                __________________________________________________________________________

Within Table 1B, like reference characters designate identical orcorresponding parts shown within Table 1A, and in addition, A designatesa particular speed range, B designates an element of the planetary gearset, N designates the number of revolutions of the elements, and Wdesignates the tangential force thereof. As the reduction gear ratio ofthe fourth forward speed range F₄ is 1 : 1.00, the number of revolutionsN of each sun gear, ring gear, and carrier is 1.00, the number ofrevolutions N of an individual sun gear, ring gear and carrier is 1.00,and the number of revolutions N of each planetary gear is 0.00.

The tangential forces W are therefore considerably less than thoseproduced within the other speed ranges wherein the torque of the inputshaft is transmitted to all of the elements through means of only oneengaged clutch, while to the contrary, the torque of the input shaft ofthe fourth speed range F₄ is distributed to all elements as a result ofengaging at least two clutches, and accordingly, it is clear that theresulting tangential forces of the elements of such speed range aresmaller than those produced as a result of the transmission of torquefrom the input shaft as a result of coupling only one clutch.Hereinafter, a discussion of the number of revolutions N and thetangential forces W within the speed range having the reduction gearratio of 1 : 1.00 will be omitted.

Referring now to FIG. 2, there is shown another embodiment of thepresent invention wherein a fourth planetary gear set, generallyindicated by the reference character X₄, of the single-pinion type isinterposed between the third planetary gear set X₃ and the output shaft,such fourth planetary gear set X₄ including a fourth sun gear S₄connected to the output shaft as well as to the third carrier C₃, afourth planetary gear P₄ engaged with the fourth sun gear S₄, a fourthring gear RG₄ enmeshed with the fourth planetary gear P₄, and a fourthcarrier C₄ rotatably supporting the fourth planetary gear P₄. The fourthring gear RG₄ is also drivingly coupled with the third ring gear RG₃ andthe second sun gear S₂, and is additionally locked to the gear casingwhen the second brake B2 is actuated. A third brake B3 is alsointerposed between the fourth carrier C₄ and the gear casing so as to becapable of locking the former to the latter when the brake is actuated.

The following formula is given as characteristic of the fourth planetarygear set X₄ :

    n.sub.rg.sbsb.4 - (1 + i.sub.4)n.sub.c.sbsb.4 + i.sub.4 n.sub.s.sbsb.4 = 0

wherein:

N_(rg).sbsb.4 = the number of revolutions of the fourth ring gear;

N_(c).sbsb.4 = the number of revolutions of the fourth carrier;

N_(s).sbsb.4 = the number of revolutions of the fourth sun gear; and

I₄ = the radial ratio of the fourth ring gear to the fourth sun gear.

                  TABLE 2A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·                   ·                                                                         5.40                                    F2  ·              ·                                                                              3.82                                    F3         ·            ·                                                                         2.89                                    F4         ·       ·                                                                              2.21                                    F5                ·     ·                                                                         1.76                                    F6                ·                                                                              ·                                                                              1.48                                    F7  ·    ·          1.00                                    R1  ·         ·     -4.82                                   R2         ·  ·     -1.50                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.562, and Table 2A shows the relationship between the operation of allof the clutches CL₁, CL₂, and CL₃ and brakes B₁, B₂ and B₃ with respectto the reduction gear ratio within each speed range, while Table 2Bshows the relationship regarding the number of revolutions and thetangential forces of the elements of the planetary gear sets within eachspeed range.

                                      TABLE 2B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.54                                                                             0.33                                                                             -0.77                                                                             -0.10                                                                             0.19                                                                              0.33                                                                             0.54                                                                             1.00                                                                             0.19                                                                              -0.10                                                                             -0.90                                                                             0.19                                                                              0.00                                                                              -0.10                                                                             -0.48              F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.0 0.0                                                                              0.0                                                                              2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              2.82                                                                              5.63                                                                              2.82                                                                              2.82                  N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             0.26                                                                              0.09                                                                              0.0 -0.43              F2 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.0 0.0 0.0                   N 1.87                                                                             1.00                                                                             0.61                                                                             -1.43                                                                             -0.19                                                                             0.35                                                                              0.61                                                                             1.01                                                                             1.87                                                                             0.35                                                                              -0.19                                                                             -1.68                                                                             0.35                                                                              0.00                                                                              -0.19                                                                             -0.89              F3 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              1.21                                                                              2.42                                                                              1.21                                                                              1.21                  N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             0.45                                                                              0.16                                                                              0.0 -0.74              F4 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                   N 3.08                                                                             1.65                                                                             1.00                                                                             -2.36                                                                             -0.32                                                                             0.57                                                                              1.00                                                                             1.67                                                                             3.08                                                                             0.57                                                                              -0.32                                                                             -2.76                                                                             0.57                                                                              0.00                                                                              -0.32                                                                             -1.46              F5 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.48                                                                              0.97                                                                              0.48                                                                              0.48                  N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                                                                             0.67                                                                              0.24                                                                              0.0 -1.11              F6 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.0 0.0 0.0 0.0                   N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             -0.21                                                                             -0.48                                                                             -0.64                                                                             -0.70              R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.87                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.0 0.0 0.0                   N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                                                                             -0.67                                                                             -1.55                                                                             -2.04                                                                             -2.26              R2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                __________________________________________________________________________

Referring now to FIG. 3, yet another embodiment of the present inventionis disclosed wherein the fourth planetary gear set X₄ of thesingle-pinion type includes a fourth sun gear S₄ drivingly engaged withthe third ring gear RG₃, while the fourth ring gear RG₄ is drivinglyengaged with the output shaft. The fourth sun gear S₄ is thus capable ofbeing locked to the gear casing when the second brake B2 is actuated,and a third brake B3 is interposed between the fourth carrier C₄ and thegear casing so as to be capable of locking the same thereto when thebrake B3 is actuated.

                  TABLE 3A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·                   ·                                                                         8.83                                    F2         ·            ·                                                                         4.36                                    F3  ·              ·                                                                              3.82                                    F4         ·       ·                                                                              2.21                                    F5                ·                                                                              ·                                                                              1.48                                    F6  ·    ·          1.00                                    R1  ·         ·     -4.82                                   R2         ·  ·     -1.50                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.562 and Table 3A shows the relationship between the operation of theclutches and brakes with respect to the reduction gear ratios withineach speed range, while Table 3B shows the relationship regarding thenumber of revolutions and the tangential forces of the elements of theplanetary gear sets within each speed range.

                                      TABLE 3B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.49                                                                             0.27                                                                             -0.83                                                                             -0.20                                                                             0.11                                                                              0.27                                                                             0.59                                                                             1.00                                                                             0.11                                                                              -0.20                                                                             -0.98                                                                             -0.20                                                                             -0.00                                                                             0.11                                                                              0.52               F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.0 0.0                                                                              0.0                                                                              2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              5.01                                                                              10.02                                                                             5.01                                                                              5.01                  N 2.02                                                                             1.00                                                                             0.54                                                                             -1.69                                                                             -0.41                                                                             0.23                                                                              0.54                                                                             1.19                                                                             2.02                                                                             0.23                                                                              -0.41                                                                             -1.97                                                                             -0.41                                                                             -0.00                                                                             0.23                                                                              1.05               F2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              2.15                                                                              4.31                                                                              2.15                                                                              2.15                  N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             0.0 0.17                                                                              0.26                                                                              0.43               F3 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.0 0.0 0.0                   N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             0.0 0.29                                                                              0.45                                                                              0.74               F4 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                   N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                                                                             0.0 0.43                                                                              0.67                                                                              1.11               F5 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.0 0.0 0.0 0.0                   N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             -0.64                                                                             -0.86                                                                             -0.21                                                                             0.70               R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.00                                                                              0.0 0.0 0.0                   N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                                                                             -2.04                                                                             -1.16                                                                             -0.67                                                                             2.26               R2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.00                                                                              0.0 0.0 0.0                __________________________________________________________________________

A fourth embodiment of a speed change gear system constructed inaccordance with the present invention is illustrated within FIG. 4 andis seen to include a fourth planetary gear set X₄ of the single-piniontype interposed between the third planetary gear set X₃ and the outputshaft, the fourth carrier C₄ being drivingly engaged with the third ringgear RG₃ and the second sun gear S₂ so as to be capable of being lockedto the gear casing when the second brake B2 is actuated. The third brakeB3 is interposed between the fourth sun gear S4 and the gear casing soas to be capable of locking the same thereto when the brake B3 isactuated, and the fourth ring gear RG₄ is drivingly engaged with thethird carrier C₃ as well as the output shaft.

                  TABLE 4A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·              ·                                                                              3.82                                    F2         ·       ·                                                                              2.21                                    F3  ·                   ·                                                                         2.01                                    F4                ·                                                                              ·                                                                              1.48                                    F5         ·            ·                                                                         1.44                                    F6                ·     ·                                                                         1.17                                    F7  ·    ·          1.00                                    R1  ·         ·     -4.82                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.562, and Table 4A shows the relationship between the operation of theclutches and brakes with respect to the reduction gear ratio within eachspeed range, while Table 4B shows the relationship regarding the numberof revolutions and the tangential forces of all of the elements of theplanetary gear sets within each speed range.

                                      TABLE 4B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             -0.47                                                                             0.0 0.26                                                                              1.20               F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.0                                                                              0.0                                                                              2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.00                                                                              0.00                                                                              0.00                  N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             -0.81                                                                             0.0 0.45                                                                              2.07               F2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.00                                                                              0.00                                                                              0.00                  N 1.00                                                                             0.71                                                                             0.58                                                                             -0.47                                                                             0.32                                                                              0.50                                                                              0.58                                                                             0.34                                                                             1.00                                                                             0.50                                                                              0.32                                                                              -0.55                                                                             0.0 0.32                                                                              0.50                                                                              0.82               F3 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              1.80                                                                              3.61                                                                              1.80                                                                              1.80                  N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                                                                             -1.20                                                                             0.0 0.67                                                                              3.08               F4 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.0 0.00                                                                              0.00                                                                              0.00                  N 1.40                                                                             1.00                                                                             0.82                                                                             -0.66                                                                             0.45                                                                              0.70                                                                              0.82                                                                             0.47                                                                             1.40                                                                             0.70                                                                              0.45                                                                              -0.78                                                                             0.0 0.45                                                                              0.70                                                                              1.14               F5 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.77                                                                              1.55                                                                              0.77                                                                              0.77                  N 1.71                                                                             1.22                                                                             1.00                                                                             -0.81                                                                             0.55                                                                              0.85                                                                              1.00                                                                             0.57                                                                             1.71                                                                             0.85                                                                              0.55                                                                              -0.95                                                                             0.0 0.55                                                                              0.85                                                                              1.40               F6 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.31                                                                              0.62                                                                              0.31                                                                              0.31                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             -1.40                                                                             -0.64                                                                             -0.21                                                                             1.96               R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.00                                                                              0.00                                                                              0.00               __________________________________________________________________________

Referring now to FIG. 5, a further embodiment of the invention isdisclosed wherein the fourth planetary gear set X₄, of the single-piniontype is interposed between the third planetary gear set X₃ and theoutput shaft and wherein further the fourth carrier C₄ is drivinglyengaged with the third ring gear RG₃ and the second sun gear S₂ so as tobe capable of being locked to the gear casing when the second brake B2is actuated. The third brake B3 is is interposed between the fourth ringgear RG₄ and the gear casing so as to be capable of locking the samethereto when the brake B3 is in fact actuated, and the fourth sun gearS₄ is drivingly engaged with the output shaft.

                  TABLE 5A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·              ·                                                                              3.82                                    F2  ·                   ·                                                                         2.80                                    F3         ·       ·                                                                              2.21                                    F4         ·            ·                                                                         1.78                                    F5                ·                                                                              ·                                                                              1.48                                    F6                ·     ·                                                                         1.31                                    F7  ·    ·          1.00                                    R1  ·         ·     -4.82                                   R2         ·  ·     -1.50                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.562, and Table 5A shows the relationship between the operation of theclutches and brakes with respect to the reduction gear ratio within eachspeed range, while Table 5B shows the relationship regarding the numberof revolutions and the tangential forces of the elements within theplanetary gear sets within each speed range.

                                      TABLE 5B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.00                                                                              0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.00                                                                              -0.81                                                                             0.26                                                                              0.00                                                                               -0.15                                                                            -0.67              F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.0                                                                              0.0                                                                              2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00                  N 1.00                                                                             0.63                                                                             0.47                                                                             -0.61                                                                             0.13                                                                              0.36                                                                              0.47                                                                             0.43                                                                             1.00                                                                             0.36                                                                              0.13                                                                              -0.71                                                                             0.36                                                                              0.13                                                                              0.0 -0.59              F2 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.0                                                                              0.0                                                                              2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              1.80                                                                              3.61                                                                              1.80                                                                              1.80                  N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.00                                                                              0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.00                                                                              -1.40                                                                             0.45                                                                              0.00                                                                              -0.25                                                                             -1.16              F3 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00                  N 1.58                                                                             1.00                                                                             0.74                                                                             -0.96                                                                             0.20                                                                              0.56                                                                              0.74                                                                             0.68                                                                             1.58                                                                             0.56                                                                              0.20                                                                              -1.12                                                                             0.56                                                                              0.20                                                                              0.0 -0.93              F4 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.77                                                                              1.55                                                                              0.77                                                                              0.77                  N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                                                                             0.67                                                                              0.00                                                                              -0.38                                                                             -1.73              F5 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.0 0.00                                                                              0.00                                                                              0.00                  N 2.14                                                                             1.35                                                                             1.00                                                                             -1.30                                                                             0.27                                                                              0.76                                                                              1.00                                                                             0.92                                                                             2.14                                                                             0.76                                                                              0.27                                                                              -1.52                                                                             0.76                                                                              0.27                                                                              0.0 -1.25              F6 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.31                                                                              0.62                                                                              0.31                                                                              0.31                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             -0.21                                                                             -0.64                                                                             -0.88                                                                             -1.10              R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.00                                                                              0.0 0.0                   N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                                                                             -0.67                                                                             -204                                                                              -2.82                                                                             -3.53              R2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00               __________________________________________________________________________

Turning now to the embodiment illustrated within FIG. 6, the fourthplanetary gear set X₄ of the single-pinion type is seen to be interposedbetween the third planetary gear set X₃ and the output shaft and is seento include the fourth sun gear S₄ drivingly engaged with the third ringgear RG₃ and the second sun gear S₂ so as to be capable of being lockedtherewith to the gear casing when the second brake B2 is actuated. Thethird brake B3 is interposed between the fourth ring gear RG₄ and thecasing so as to be capable of locking the fourth ring gear RG₄ theretowhen the brake B3 is actuated, and the fourth carrier C₄ is drivinglyengaged with the output shaft.

                  TABLE 6A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·              ·                                                                              3.82                                    F2         ·       ·                                                                              2.21                                    F3                ·                                                                              ·                                                                              1.48                                    F4  ·    ·          1.00                                    R1  ·                   ·                                                                         -5.45                                   R2  ·         ·     -4.82                                   R3         ·            ·                                                                         -1.77                                   R4         ·  ·     -1.50                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.437 and Table 6A shows the relationship between the operation of theclutches and brakes with respect to the reduction gear ratio within eachspeed range, while Table 6B shows the relationship regarding the numberof revolutions and the tangential forces of the elements of theplanetary gear sets within each speed range.

                                      TABLE 6B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             0.0 0.26                                                                              0.38                                                                              0.41               F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.0 0.0 0.0                   N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             0.0 0.45                                                                              0.65                                                                              0.70               F2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                   N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                                                                             0.0 0.67                                                                              0.97                                                                              1.05               F3 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.0 0.0 0.0 0.0                   N 1.00                                                                             0.32                                                                             0.02                                                                             -1.11                                                                             -0.60                                                                             -0.18                                                                             0.02                                                                             0.79                                                                             1.00                                                                             -0.18                                                                             -0.60                                                                             - 1.30                                                                            -0.60                                                                             -0.18                                                                             0.00                                                                              0.65               R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              6.45                                                                              12.89                                                                             6.45                                                                              6.45                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             -0.64                                                                             -0.21                                                                             -0.02                                                                             0.67               R2 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.00                                                                              0.0 0.0 0.0                   N 3.08                                                                             1.00                                                                             0.06                                                                             -3.43                                                                             -1.86                                                                             -0.57                                                                             0.06                                                                             2.43                                                                             3.08                                                                             -0.57                                                                             -1.86                                                                             -4.01                                                                             -1.86                                                                             -0.57                                                                             0.0 2.01               R3 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              2.77                                                                              5.54                                                                              2.77                                                                              2.77                  N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                                                                             -2.04                                                                             -0.67                                                                             -0.06                                                                             2.14               R4 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.00                                                                              0.0 0.0 0.0                __________________________________________________________________________

Referring now to the embodiment of the invention illustrated within FIG.7, the fourth planetary gear set X₄ of the single-pinion type isinterposed between the third planetary gear set X₃ and the output shaftand includes the fourth ring gear RG₄ drivingly engaged with the thirdring gear RG₃ and the second sun gear S₂ so as to be capable of beinglocked therewith to the gear casing when the second brake B2 isactuated. The third brake B3 is interposed between the fourth sun gearS₄ and the casing so as to be capable of locking the fourth sun gear S₄thereto when the brake B3 is actuated, and the fourth carrier C₄ isdrivingly engaged with the output shaft.

                  TABLE 7A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1                    3.82                                                    F2                    2.21                                                    F3                    1.48                                                    F4                    1.00                                                    F5                    0.73                                                    R1                    -4.82                                                   R2                    -1.50                                                   R3                    -0.58                                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.562, and Table 7A shows the relationship between the operation of theclutches and brakes with respect to the reduction gear ratio within eachspeed range, while Table 7B shows the relationship regarding the numberof revolutions and the tangential forces of all of the elements of theplanetary gear sets within each speed range.

                                      TABLE 7B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 R4                 __________________________________________________________________________       N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             0.73                                                                              0.26                                                                              0.0 -1.20              F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.0 0.0 0.0                   N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             1.26                                                                              0.45                                                                              0.0 -2.07              F2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                   N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.0 -2.09                                                                             1.87                                                                              0.67                                                                              0.0 -3.08              F3 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.0 0.0 0.0 0.0                   N -0.80                                                                            0.44                                                                             1.00                                                                             2.05                                                                              2.15                                                                              1.37                                                                              1.00                                                                             -1.45                                                                            -0.80                                                                            1.37                                                                              2.15                                                                              2.39                                                                              0.0 1.37                                                                              2.15                                                                              3.53               F5 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.48                                                                              0.97                                                                              0.48                                                                              0.48                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             0.56                                                                              -0.21                                                                             -0.64                                                                             -1.96              R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.0 0.0 0.0                   N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                                                                             1.78                                                                              -0.67                                                                             -2.04                                                                             -6.29              R2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                   N 1.00                                                                             -0.55                                                                            -1.25                                                                            -2.55                                                                             -2.68                                                                             -1.71                                                                             -1.25                                                                            1.81                                                                             1.00                                                                             -1.71                                                                             -2.68                                                                             -2.99                                                                             0.0 -1.71                                                                             -2.68                                                                             -4.40              R3 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.00                                                                              0.00                                                                              0.0                                                                              0.0                                                                              2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              2.82                                                                              5.63                                                                              2.82                                                                              2.82               __________________________________________________________________________

Referring now to FIG. 8 still another embodiment of the presentinvention is disclosed wherein the fourth planetary gear set X₄ of thesingle-pinion type is interposed between the third planetary gear set X₃and the output shaft and is seen to include the fourth ring gear RG₄drivingly engaged with the first and third sun gears S₁ and S₃, and thefourth sun gear S₄ is operatively connected to the third brake B3.Consequently, as the third brake B3 is interposed between the fourth sungear S₄ and the gear casing, such is capable of locking the fourth sungear S₄ to the casing when the brake B3 is actuated, the fourth carrierC₄ being drivingly engaged with the output shaft.

                  TABLE 8A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·              ·                                                                              3.82                                    F2         ·       ·                                                                              2.21                                    F3  ·                   ·                                                                         1.28                                    F4         ·            ·                                                                         1.12                                    F5                ·     ·                                                                         1.05                                    F6  ·    ·          1.00                                    R1  ·         ·     -4.82                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.280, and Table 8A shows the relationship between the operation of theclutches and brakes and the reduction gear ratio within each speedrange, while Table 8B shows the relationship regarding the number ofrevolutions and the tangential forces of all the elements of theplanetary gear sets within each speed range.

                                      TABLE 8B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             -2.37                                                                             0.26                                                                              1.00                                                                              2.05               F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.00                                                                              0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.00                                                                              0.00                                                                              0.00                  N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             -4.10                                                                             0.45                                                                              1.73                                                                              3.54               F2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.0 0.0 0.0 0.0                   N 1.00                                                                             0.88                                                                             0.82                                                                             -0.21                                                                             0.70                                                                              0.78                                                                              0.82                                                                             0.15                                                                             1.00                                                                             0.78                                                                              0.70                                                                              -0.24                                                                             0.0 0.78                                                                              1.00                                                                              0.61               F3 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.00                                                                              0.00                                                                              0.00                                                                             0.00                                                                             0.00                                                                             0.00                                                                              0.00                                                                              0.00                                                                              1.00                                                                              2.00                                                                              1.00                                                                              1.00                  N 1.14                                                                             1.00                                                                             0.94                                                                             -0.24                                                                             0.80                                                                              0.89                                                                              0.94                                                                             0.17                                                                             1.14                                                                             0.89                                                                              0.80                                                                              -0.28                                                                             0.0 0.89                                                                              1.14                                                                              0.69               F4 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.33                                                                             0.67                                                                              0.33                                                                              0.33                                                                              0.43                                                                              0.86                                                                              0.43                                                                              0.43                  N 1.22                                                                             1.07                                                                             1.00                                                                             -0.25                                                                             0.86                                                                              0.95                                                                              1.00                                                                             0.18                                                                             1.22                                                                             0.95                                                                              0.86                                                                              -0.29                                                                             0.00                                                                              0.95                                                                              1.22                                                                              0.74               F5 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.48                                                                             0.97                                                                              0.48                                                                              0.48                                                                              0.17                                                                              0.34                                                                              0.17                                                                              0.17                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             -4.52                                                                             -0.21                                                                             1.00                                                                              3.35               R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.00                                                                              0.00                                                                              0.00               __________________________________________________________________________

Turning now to FIG. 9, a still further embodiment of the presentinvention is illustrated wherein the fourth planetary gear set X₄ of thesingle-pinion type is interposed between the third planetary gear set X₃and the output shaft, and the fourth sun gear S₄ is drivingly engagedwith the first and third sun gears S₁ and S₃. The third brake B3 isinterposed between the fourth ring gear RG₄ and the gear casing so as tobe capable of locking the fourth ring gear RG₄ thereto when the brake B3is actuated, and the fourth carrier C₄ is drivingly engaged with theoutput shaft.

                  TABLE 9A                                                        ______________________________________                                        CL1    CL2    CL3    B1   B2   B3   Reduction Gear Ratio                      ______________________________________                                        F1  ·                   ·                                                                         4.57                                    F2  ·              ·                                                                              3.82                                    F3         ·            ·                                                                         2.53                                    F4         ·       ·                                                                              2.21                                    F5                ·     ·                                                                         1.61                                    F6                ·                                                                              ·                                                                              1.48                                    F7  ·    ·          1.00                                    R1  ·         ·     -4.82                                   R2         ·  ·     -1.50                                   ______________________________________                                    

Within this embodiment, the radial ratio within each speed range is I₄ =0.280 and Table 9A shows the relationship between the operation of theclutches and brakes and the reduction gear ratio within each speedrange, while Table 9B shows the relationship regarding the number ofrevolutions and the tangential forces of all of the elements ofplanetary gear sets within each speed range.

                                      TABLE 9B                                    __________________________________________________________________________    B    X1           X2            X3             X4                             A    S1 C1 RG1                                                                              P1  S2  C2  RG2                                                                              P2 S3 C3  RG3 P3  S4  C4  RG4 P4                 __________________________________________________________________________       N 1.00                                                                             0.55                                                                             0.35                                                                             -0.74                                                                             -0.06                                                                             0.22                                                                              0.35                                                                             0.52                                                                             1.00                                                                             0.22                                                                              -0.06                                                                             -0.86                                                                             1.00                                                                              0.22                                                                              0.0 -0.61              F1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.00                                                                              0.00                                                                              0.00                                                                             0.00                                                                             0.0                                                                              0.00                                                                              0.00                                                                              0.00                                                                              3.57                                                                              7.14                                                                              3.57                                                                              3.57                  N 1.00                                                                             0.58                                                                             0.39                                                                             -0.69                                                                             0.0 0.26                                                                              0.39                                                                             0.49                                                                             1.00                                                                             0.26                                                                              0.0 -0.81                                                                             1.00                                                                              0.26                                                                              0.06                                                                              -0.57              F2 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 0.0 0.00                                                                              0.00                                                                             0.00                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.00                                                                              0.0 0.0 0.0                   N 1.80                                                                             1.00                                                                             0.64                                                                             -1.33                                                                             -0.11                                                                             0.39                                                                              0.64                                                                             0.94                                                                             1.80                                                                             0.39                                                                              -0.11                                                                             -1.55                                                                             1.80                                                                              0.39                                                                              0.0 -1.10              F3 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.33                                                                             0.67                                                                              0.33                                                                              0.33                                                                              1.53                                                                              3.07                                                                              1.53                                                                              1.53                  N 1.73                                                                             1.00                                                                             0.67                                                                             -1.20                                                                             0.0 0.45                                                                              0.67                                                                             0.85                                                                             1.73                                                                             0.45                                                                              0.0 -1.40                                                                             1.73                                                                              0.45                                                                              0.10                                                                              -0.99              F4 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              0.69                                                                              1.38                                                                              0.69                                                                             0.69                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.00                                                                              0.0 0.0 0.0                   N 2.83                                                                             1.57                                                                             1.00                                                                             -2.08                                                                             -0.17                                                                             0.62                                                                              1.00                                                                             1.47                                                                             2.83                                                                             0.62                                                                              -0.17                                                                             -2.44                                                                             2.83                                                                              0.62                                                                              0.0 -1.72              F5 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.48                                                                             0.97                                                                              0.48                                                                              0.48                                                                              0.61                                                                              1.23                                                                              0.61                                                                              0.61                  N 2.57                                                                             1.49                                                                             1.00                                                                             -1.79                                                                             0.0 0.67                                                                              1.00                                                                             1.26                                                                             2.57                                                                             0.67                                                                              0.00                                                                              -2.09                                                                             2.57                                                                              0.67                                                                              0.14                                                                              -1.48              F6 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 1.00                                                                              2.00                                                                              1.00                                                                             1.00                                                                             0.00                                                                             0.00                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00                  N 1.00                                                                             0.31                                                                             0.0                                                                              -1.14                                                                             -0.64                                                                             -0.21                                                                             0.0                                                                              0.80                                                                             1.00                                                                             -0.21                                                                             -0.64                                                                             -1.33                                                                             1.00                                                                              -0.21                                                                             -0.55                                                                             -0.94              R1 W 0.0                                                                              0.0                                                                              0.0                                                                              0.0 5.82                                                                              11.64                                                                             5.82                                                                             5.82                                                                             2.82                                                                             5.63                                                                              2.82                                                                              2.82                                                                              0.0 0.00                                                                              0.00                                                                              0.00                  N 3.21                                                                             1.00                                                                             0.0                                                                              -3.65                                                                             -2.04                                                                             -0.67                                                                             0.0                                                                              2.58                                                                             3.21                                                                             -0.67                                                                             -2.04                                                                             -4.27                                                                             3.21                                                                              -0.67                                                                             -1.75                                                                             -3.02              R2 W 0.69                                                                             1.38                                                                             0.69                                                                             0.69                                                                              1.81                                                                              3.62                                                                              1.81                                                                             1.81                                                                             0.88                                                                             1.75                                                                              0.88                                                                              0.88                                                                              0.00                                                                              0.00                                                                              0.00                                                                              0.00               __________________________________________________________________________

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the presentinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by letters patent ofthe United States is:
 1. A speed change gear system comprising:an inputshaft; an output shaft; a first planetary gear set including a first sungear, a first planetary gear meshed with said first sun gear, a firstring gear meshed with said first planetary gear, and a first carrierrotatably supporting said first planetary gear; a second planetary gearset including a second sun gear, a second planetary gear meshed withsaid second sun gear, a second ring gear meshed with said secondplanetary gear and drivingly connected to said first ring gear, and asecond carrier rotatably supporting said second planetary gear; a thirdplanetary gear set including a third sun gear drivingly connected tosaid first sun gear, a third planetary gear meshed with said third sungear, a third ring gear meshed with said third planetary gear anddrivingly connected to said second sun gear, and a third carrierrotatably supporting said third planetary gear and drivingly connectedto said second carrier and said output shaft; clutch means forselectively coupling said first and third sun gears, said first carrier,and said first and second ring gear to said input shaft; and brake meansactuatable for selective engagement with said first and second ringgears, said second sun gear and said third ring gear.
 2. A speed changegear system in accordance with claim 1 wherein said clutch meansincludes a first clutch for connecting said first and third sun gearswith said input shaft, a second clutch for connecting said first carrierwith said input shaft, and a third clutch for connecting said first andsecond ring gears with said input shaft.
 3. A speed change gear systemin accordance with claim 2 wherein said brake means includes a firstbrake selectively engageable with said first and second ring gears, anda second brake selectively engageable with said second sun gear and saidthird ring gear.
 4. A speed change gear system in accordance with claim1 which further comprises:a fourth planetary gear set including a fourthsun gear drivingly connected to said output shaft, a fourth planetarygear meshed with said fourth sun gear, a fourth ring gear meshed withsaid fourth planetary gear and drivingly connected to said third ringgear, and a fourth carrier rotatably supporting said fourth planetarygear; and further brake means actuatable for selective engagement withsaid fourth carrier.
 5. A speed change gear system in accordance withclaim 4 wherein said brake means includes a first brake selectivelyengageable with said first and second ring gears, and a second brakeselectively engageable with said fourth carrier.
 6. A speed change gearsystem in accordance with claim 4 wherein said brake means includes afirst brake selectively engageable with said first and second ringgears, a second brake selectively engageable with said second sun gearand said third ring gear, and a third brake selectively engageable withsaid fourth carrier.
 7. A speed change gear system in accordance withclaim 1 which further comprises:a fourth planetary gear set including afourth sun gear drivingly connected to said third ring gear, a fourthplanetary gear meshed with said fourth sun gear, a fourth ring gearmeshed with said fourth planetary gear and drivingly connected to saidoutput shaft, and a fourth carrier rotatably supporting said fourthplanetary gear; and further brake means actuatable for selectiveengagement with said fourth carrier.
 8. A speed change gear system inaccordance with claim 7 wherein said brake means includes a first brakeselectively engageable with said first and second ring gears, a secondbrake selectively engageable with said second sun gear and said thirdring gear, and a third brake selectively engageable with said fourthcarrier.
 9. A speed change gear system in accordance with claim 1 whichfurther comprises:a fourth planetary gear set including a fourth sungear, a fourth planetary gear meshed with said fourth sun gear, a fourthring gear meshed with said fourth planetary gear and drivingly connectedto said third ring gear, and a fourth carrier rotatably supporting saidfourth planetary gear and drivingly connected to said output shaft; andfurther brake means actuatable for selective engagement with said fourthsun gear.
 10. A speed change gear system in accordance with claim 9wherein said brake means includes a first brake selectively engageablewith said first and second ring gears, a second brake selectivelyengageable with said second sun gear and said third ring gear, and athird brake selectively engageable with said fourth sun gear.
 11. Aspeed change gear system in accordance with claim 1 which furthercomprises:a fourth planetary gear set including a fourth sun geardrivingly connected to said third sun gear, a fourth planetary gearmeshed with said fourth sun gear, a fourth ring gear meshed with saidfourth planetary gear, and a fourth carrier drivingly supporting saidfourth planetary gear and drivingly connected to said output shaft; andfurther brake means actuatable for selective engagement with said fourthring gear.
 12. A speed change gear system in accordance with claim 11wherein said brake means includes a first brake selectively engageablewith said first and second ring gears, and a second brake selectivelyengageable with said fourth ring gear.
 13. A speed change gear system inaccordance with claim 11 wherein said brake means includes a first brakeselectively engageable with said first and second ring gears, a secondbrake selectively engageable with said second sun gear and said thirdring gear, and a third brake selectively engageable with said fourthring gear.